Screw-propeller pump.



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P. MARBURG, JR.

PATBNTED DEC. 3, 1907.

SCREW PROPELLBR PUMP.

APPLICATION FILED AUG.4. 1903.

3 SHEETS--SHEET l.

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k '5T y N L N xw F. MARBURG, JB.

SCREW PROPELLBR PUMP. APPLIOATIOH vFILED AUG. 4. 190s.

PATBNTED DBG. 3, 1907.

3 SHEETS-SHEET 2.

a). 544 a4/LIFO@ I I y 72 @il 35H4; @Heaney K7 No. 872,361. PATENTED DEC. 3, 1907. P. MARBURG, Jn.. SCREW PROPELLBR PUMP. APPLICATION FILED AUG.4.1903.

8 SHEETS-SHEET 3.

J ib( gy the screwfwheel; the l'irst ligure being a side 'and 2 are axial longitudinal sections of a FRANZ MARBURG, JR.,

OF NEW YORK, N. Y.

SCREW-PROPELLER PUMP.

T o all whom it 'may concern:

Be it known that l, AFRANZ MARBURG, Jr., residing in the borough oi Brooklyn., in the county of Kings and city and State of New York, haveinvented certain new and useful Improvements in Seien/Propeller Pumps, oi' Which the following is a specification.

This invention relates to the class of pumps wherein the llluid, liquid or aeriform, passing through the same, is acted upon by the spiral blades et a rotatable screw or screws on a shaft extending through the casing; and the object oi' the invention is, in part, to improve the elliciency ci' the device and also to product` higher pressure than has heretofore been obtained, so far as known in this class of pumps, by the construction of the screw or screws, as will be hereinafter eX- plaine'd; and. in part to improve the means employed l'for balancing the enrbthrust on the shaft,

In the accompanyingdrawings: Figures 1 pump embodying the invent-ion, the 'former being a horizontal andthe latter a vertical section. Fig. '3 is a plan of thel same. Figs. 4, 5 and 6 are transverse sections taken respectively at lines w, mi, and x in Fig. 2. Fig. 7 is a transverse section of the dia phragm-director, detached, the plane of the section being at line or? in Fig. 2. Figs. 8, 9 and lO illustrate a slightly modified l,term of elevation and the last two end views.

In the said drawings, l is thc main casing or body oi the pump, 2 the receiving head, and S the opposite head of said casing. 4 isv the shaft, which has rotative bearings in the heads.

5 is the inlet Jfor the Yliuid and 6, the outlet.

In the center oi'` the casing is a fixed diaphragm-director T, which will be more par ticularly described hereinafter. The `l'luid enters` the casing at the inlet 5, is driven towardfthe center of the casing hy a screw 8a on the shaft; impinges on the director 7 and passesthrough a by-pass 9 to the opposite endet` the casing; is taken by another screw Sb, oli-'the shaft, and driven n-toward the l center; impinges 0n the opposite face ot the l director 7 and passes off thence at the outlet 6. The diaphragm-director 7 is so-called l as it is so .fixed in the casing l. to cut oil direct communication hete-'ecn the inlet and outlet, compelling the iluid to pass from the l inner end of the screw S to the outer end ot Specification of Letters Patent. pplication tiled August 4. 1903. Serial No. 168.159.

-pump-inlet.

Patented Dec. 8, 1907. I

the screw 8h through the by-pass, and its ends or faces are spirally formed, the spiral being opposite to that oi the blades of the adjacent screw. As the pressures exerted by the two screws are opposed and act in an axial direction, they theoretically do not produce end-thrust on the shaft; but in practice this result is not wholly accomplished, and to balance the pressure more accurately the device now to be described is employed.

in the head at one end ol' the casing is formed a cylindrical piston chamber l0, by means of an inserted tube of metal which is concentric with the shaft 4. On the latter is 'fixed a piston 1.2 which plays in the chamy ber. Fluid from the pump-chamber, and under pressure, arrives through a pipe 11 and is admitted to a lateral chamber 13 adjacent' to the cylindrical chamber l0, and enters the piston chamber through two ports 14, 14, (Fig. i) in the tube at the respectivo ends ol the piston-chamber and always open. Opposite to the inlet-ports 14 is an exhaust-port 15 the length of this outlet or exhaust-port is equal to the length oi the. piston, and it opens into a passage 16 connecting with the Normally the piston closes this exhaust-port 15, and occupies a position between the inlet-ports 111., so that the pressure on both ends of the piston is equal. If the piston is shifted in either direction, it opens the exhaust-port on the opposite side and thus relieves the pressure on that side of the piston whereby the latter is shifted back.

again. The movement ot the piston-land consequently the endwise movement of the shaft-Tis ot' course very slight, and practically the shaft is held by this device against endwise movement.

'.lhe screws 8 and 8l will be preferably alike, except as to the spiral blades on one having an obliquity opposite to those on the other. it may be preferable that thecasing should be internally` cylindrical, the outer contour ol the screw-wheel being in this case correspondingly cylindrical, which willallow ol some end wise play of the screws and oi`l the shalt, which is desirable it thc particular balancing arrangement shown herein is to be used in combination with the screw-wheels. As shown herein the casing is cylindrical interiorly, the outer contour ot' the main por tion ot' the blades being cylindrical; but the core or body ol the screw is tapered toward its inner or delivery end, and a portion y oi this inner cnd is naked. Thus as the vIiuid lli n rents..

screw-inlet an tion of the screw-inleteto the screw-outlet' 7 of the pump,

.the blades, and as a result llows from the outer to the'inner end of the screw it linds more space to Ylill and moves with less speed in an axial direction. As .the speed of the iluid decreases, the speed in an axial direction of the screw blades remaining the same, it will be obvious that the difler ence of speed between the two will increase and consequently, under known rules, the pressureofI the fluid will increase. -Thus the iiuid enters the screw without a sudden change of pressure and the pressure gradu-V ally increaseswithin the screw and is greatest at the screw-outlet.

Pum s ol' this t* e have a large amount of unavoidable slip oi the fluid under considerable ressure-= By underslipis herein understoody the relative backilowof the fluid within the screw and in the direction of the spiral blades, in other words, slip is the difference of the theoretical and actual capacity of the screw. .ln consequence of the slip, theactual ca acity ol the pump is reduced very much, glut the slip within certain limits does not constitute a positive loss inthe eiliciency but ali'ects only the actual caump, provided the slip occurs without shocks and eddy-cur-- 'llo' accomplish this latter result, is the obj ect` of this invention.

From experiments, applicant has found vthat in ordinary screw pumps, the lluid under a considerable head moves only at `from one-half to one-quarter the axial velocity of there is a heavy blow or shock while the Huid is entering the screw, and consequently sudden great periph-y eral` 'velocity andgreat whirling of the lluid follows. lt is obvious, thatvatter the lluid has attained a high peripheral velocity, the screw blades can exert little or no further pressure on the fluid in a forward direction, and the latter will be sim ly carried around with the screw peripherallg7 with little or no forward pressure or motion. To prevent this, and to prevent whirling as much as possible, the capacity of the screw herein is pacity of the gradually an made to increase gradually from the screw-- inlet toward the'screw-outlet; thus the fluid is drawn in at the screw-.inlet width an axial velocity equal, or nearly equal, tothe axialv velocity of the spiral blades at the screw-inl let. The fluid therefor enters the screw without slip, the actual capacity of the present screw eing equal to the theoretical capacity of the screw at its inlet end, but bmgon account of the slip-less than the theoretical capacity of the screw at its outlet end. The roportion of th@ theoretical increase with the discharge which .the pump operates, and said propor.

should increase with the unavoidable slip. Applicant has found that for different pressures the'screw should at`the screw outlet which screw-outlet capacity lshould pressure against,"

massi have from 2 to 4 times the screw inlet capacity. lt is clear that in 'this manner shocks are greatly reduced at the screw-inlet. By continuing the increase of capacity gradually to the screw-outlet both the unavoidable slip and the lluid pressure increases gradually, thereby the whirling within the screw is ke ty at a minimum, and a consequent higher e iciency and a higher lluid pressureis attained. ln a pump where the screw-outlet ca acity is less than the screw-inlet capacity, a 'ormer constructor has employed a screw with increased capacity at the middle portion; this is not the construction herein claimed. In the; resent construction the capacity of the lui outlet is-greater than that of thejfluidinlet, and this is deemed essential to' the proper operationof the pump.

The annular chamber ing capacity formedV about the naked portion y of the screwoody, betweenthe point where of gradually increas- `the blades of the screw terminate and the i' 'fixed director, gradually reduces the unakvoidably high eripheral velocity of the fluid after leaving tlie screw. Thus by a gradual reduction of the velocity of the fluid, the pressure of the 'fluid will be increased and power thereby saved. The director, formed on the face of the diaphragm 7, is a spiral face having an Obliquity opposite to thatvofl the blades of theadj acent screw, and it serves to further reduce the circumferential velocity of the lluid and to gradually deflect it toward the outlet of the pump.

Instead of the means shown herein for gradually decreasing the velocit of the fluid adjacent to the screw outlet, a ed director of the same construction as the one shown in my co-pending U., S. .application Ser. -No. 163,560 liled June 29, 1903, can be used. In that case a screw of a similar shape as the one 'shown inFigs. 8, 9 V ployed. v

The spiral blades of the screw, as shown in the principal drawingspand more clearly in Fi s. 8, 9 and 1G, gradually increase to their full radial width from the ends of the screw toward vits main middle portion. The object of this is to further reduce the shock land whirling ot the fluid. The expression f main middle portion or main portion of the topsig'nity that part or portion of the screw, or of the blade, which at its outer contour, is in close proximity to the cylinder wall. In this construction, the main portion or the main middle portion of the screw has blades, increase gradually and throughout in lull radial width, in the direction toward the discharge end of the screw. Thus by increasing the full radial width of the blade, the capacity of' the screw is made. to increase in the direction from the screw-inlet ltoward the screw-outlet. Wherever the expression lull radial width of the screw blade is used and 1() can be emirc screw, ,or of the screw-blade, as used herein, is

it is to signify the radial width of the blade at the main portion or at the main middle porin the diaphragm 7; and oil-holes 18 are provided to allow the oil in the chambers to reach the shaft. Gil is admitted to the charnbers through suitable holes closed by screwplugs 19. An oiling arrangement, as for example, thel one shown in my pending patent application Ser. No. 163,560, filed June 29, 1903, it desiredgnay be applied to the present pump. v

The receiving ends of the screw-bodies, which are also naked for a short distance, are

also tapered, as clearly shown in the princialviews, thus providing an easy approach of the :['luid to the annular inlet ot the screw. Figs. S, 9 and i() show a somewhat larger` 'rate oi increase oi the t'ull radial width of the spiral bladesironi the screw-inlet toward the screw-outlet. The naked end of the screw vwheel or body is omitted at the outlet endj in this construction. The screw blades preferably commence,in a scre\r'-\vheel ol" cylindrical outer contour', at the point oi the greatest diameter of the screw body and extend toward a point of the body of less diameter.

Figs. 8, Jland 1() also show more clearly than the principal figures the gradual increase ot the radial width' of the screw blades, until they attain their full radial width, that is, the gradual increase of the blades to their full radial width, trom each end toward the main portion or main middle portion o't' the screw. \The drawings show four substantially spiral blades on each screw, but this invention is not limited in this respect and it is evidentthat' one or more blades can be `used. For greater screw-diameters and for high fluid ressure, aplurality of sc re. w-blades is -prefera ile. f

The pressure or head against which the pump herein described ca nl operate, is proportional to the square oi the peripheral velocity oi the scrmv-blades or any portions thcre'lll` itiollows, that the inner portion orsection'of the blades, that is the portions nearest to the pum p-axis, must travel at a suflieient velocity to maintain the required pressure. However in that case the outer portions of the blades travel at a greater velocity `than scesi-ary to maintain the required iressure, whereby losses of eneigy of a diiierent-'nature are caused. rl`hrough @lt follows, tlzat ii the radial width ofV said blades is too large, in proportion tothe screw-du'm'ieter, the pump is very Inellicient,

either through back flow at the inner portion of the screw-blades, or through great waste of energy at the outer portions of the screwblades. It has been found by me in pumps as embodied in this invention, that the radial width of the screw-blades should be less than one-sixth part of the corresponding diameter of the outer contour of the propeller-blade, to give goed results. Whenever the expression corres ending diameter of the outer contour o the screw is used, it signifies the diameter of the outer,

contour of the screw axis at the oint at which the radial Width of the blade 1s taken. It is clear that the diameter of the outer contour might vary considerably at different points of the screw, or at diilerent vertical planes through the screw-axis. It is of special importance in a pump of a greaterscrew-outlet capacity than screw-inlet capacity, as shown herein, that the lull4 radial width of the blades should be within the above stated limits, as the capacity of this articular pump at a given number ol' revoutions por minute is about constant against different pressures, within certain limits, the slip not varying to a large degree under dilferent pressures as in ordinary screw-pumps. This 'tact ol`` a nearly constant capacity of the pump at a given number oi' revolutions per minute at diiierent pressures or heads within certain limits, constitutes a vital diflcrence' between this and ordinary screw-pumps, inaslnuch as under increasing or decreasing pressures at the pump-outlet, in ordinary screw-pumps-#unrler similar conditionsthe volume of the lluid pumped decreases or increases very largely in consequence of greatly varying slip. As the present screw is constructed with a certain proportion ol' inlet and outlet capacity, or in other words, as the screw has a given and practically constant slip, it is necessary in order to attain the best resultsto run the blade or each portion thereof while operating against acorta-in lluid pressure as nearly as possible at a certain velocity, so that the given or practically constant slip is not more nor less, than thc equivalent of the unavoidable slip under the given pressure at that velocity` In consequence of the given or constant slip of this screw, its capacity at relatively lou' pressure but at high velocity of the spiral blades, might be reduced by more, than the unavoidable slip would amount to in an ordinary screw under similar conditions, while the amount ol energy consun'ied by this screw, or by any sections of the spiral blades, as stated hcreinbehire, is proportional to the. cube ot the velocity of the' spiral blades, and is practically imlependent of the pressure at the pump outlet. The slip being practically constant within this propeller, there is furthermore at all diflerentvelocities of the screw-blade and at all pressures or lOO.

55 broadly a blade of oblique shape and `radin heads, an unavoidable high peripheral velocity of the fluid at the screw-outlet, which velocity should be gradually and without shock reduced and the usei ul pressure thereby increased. It is however clear, that this latter result can only be effectively attained, and Without any undue edd)"currents, if the fluid emerges from the screw-outlet with an approximately' uniform velocity, which in turn is only possible when -the pro ortions of the radial width ofthe screwlade is within the above limits. Unless, therefore, the radial width of the screw-blades, or spiral blades, is within the above limits, the losses through the given or constant slip for which the pump has been specially constructed, and which slip in ordinary screwpumps only takes place under a certain pressure at a certain velocity of the spiral lade, may become a disadvantage instead of an advantage. However, if the pump is run at the proper velocity for the pressure required, and if the radial width of the blades is within the proper proportions, and if fixed directors of a proper shape or other means are employed at the screw-outlet, as shown in this ap lic'ation, to gradually vreduce the unavoi able high peripheral velocity of the fluid at the screw-outlet, in that case this pump will operate with a very high efliciency. Y

The herein'stated rules have never before been explained and none of` the other manne 'facturers of this class of pumps, have at present applied them. The stated proportions of the radial Width of the spiral propeller blades of this screw, as compared with the correspof :ding diameter of .the outer contour of the spiral blades, and which is absolutely necessary'in applicants-construction, for the vsuccessful and efficient operation against moderate and particularly against high pres. sure or head, is also an entirely new feature.

A pump of this type, where the radial ,width of the blademay be constant from the screw-inlet toward the screw-outlet, but havving increasing capacity from the screw-inlet toward the screw-outlet, and having a greater screw-outlet capacity than screw-in- Ato let capacity, is'shown and claimed in my co-A pending U; S. application Serial N o. 2462275,

filed February '18th, 1905.

It should also be stated, that whenever the vexpression spiral blade or screw-blade .occurs in thiskapplication it is to signify `ally carved from the screw-inlet toward the screw-outlet. The expression screw 1s to signify broadly, a body or core having one or more spiral blades, which blades extend in the direction from the screw-inlet toward thelscrew-outlet, in a peripheral and partly axial l rrection. A scr'ewwhcel may be a screw l without or with a rotating outer ring, the latter being lshown in my co-pending applicafo r pumping elastic and incompressible fluids,

the fluid-inlet and fluid-outlet remaining the same, and the invention is not limited in this respect. l l

I herein broadly claim some of the characteristics of the pump shown while some other characteristics are claimed broadly in my co-pending U.- S. ap lications, namely: Serial No. l63,560 filed June 29, 1003; Serial No. 174,249 filed September 23rd, 1903; Serial No. 246,275, led February 1.8, 1905 and Serial No. 246,276 led February 18, 1905.

Having thus described my invention, ,l claim-- l.. .fi-1 mechanism for the purpose specified, having' a casing, a shaft rotatable in said casing, an inlet and an outlet for the fluid, and a screw on said shaft and rotative'in the casing, the said' screw having its core tapered or lconed toward its delivery end and its diameter at the periphery of its blades uniform, whereby the capacity increases'from the receiving end of.' the screw, substantially as and for the purpose set fort 2. A mechanism for the purpose specified.

having a casing with an inlet and an outlet casing with a fluid-inlet and fluid-outlet, a I

screw-wheel mounted rotatively within said casing between the fluid-inlet and outlet,

-said screw-wheel having a substantiallv spiralv blade, the full radial width of said blade and the capacity of the screw increasingfrom the screw-inlet toward the screwoutlet.

4. In a device for thepurpose set forth, a casing with a fluid-inlet and fluideoutlet, a screw-wheel fitted in and mounted rotatively` within said f l in f between the fluid-inlet and outlet, said screw-wheel having a substanlti'ally spiral blade, the full radial width of said blade and the capacity of the screw' increasing from the screw-inlet toward the screw-outlet.

5. In a device for the purpose set forth, aV

eraser 5 casing with a fluid-inlet and fluid-outlet, a I stantially spiral blade, the full radial width screw-wheeltitted in and mounted rotatively l ol said blade increasing throughout the within said casing between said lluidinlet and outlet, said screw-wheel having a subl, screw .troni its inlet, and nicans lor gradually reducing the velocity ol the lluid adjacent to l stantially s iral blade, the full radial widthl the screw-outlet. s 70 of said bla( e and the capacity ot the screw increasing throughout the screw from its inlet.

6. In a device for the purpose set forth, Aan internally cylindrical casing with a fluid-inlet and iluidoutlet, a screw-wheel with its main portion ot' cylindrical outer contour, iitted in and mounted rotatively Within said casing between the fluid-inlet and outlet, said screw- Wheel havingI a substantially spiral blade,

the full radial width ot said blade and thecapacity of the` screw increasing Afrom the screw-inlet toward the screw-outlet.

7. ln a device for the purpose set forth, an internally cylindrical casing with a fluid-inlet and fluid-outlet, a screw-wheel having at its main portieri a substantially cylindrical outer contour, fitted in and mounted rot-atively within said casing between said fluidinlet and outlet, said screw-wheel having a substantially spiral blade, the vfull radial width of said blade increasing throughout the screw from its inlet.

S. ln a device for the purposeset forth, a casing with a fluid-inlet and fluidoutlet, Ia screw-wheel mounted rotative-ly withinv said casing between vthe fluid-inlet and outlet, said screwwheel having a substantially spiral blade, the full radial Width of said blade increasing tronL the screw-inlet toward the screw-outlet, land means tor gradually reducing the velocity ol the fluid adjacent to the screw-out let. I

9. ln a' device l'or the purpose set forth, a casing with a lluid-inlet and llu1dout-let,a

screw-Wheel mounted rotatively within said casing between the lluiddnlet and fluid-ouh let, said screw-wheel having a substantially spiral blade, the tull radial width of said blade increasing throughout the screw from its inlet, and means for gradually reducing the velocity 'ot the tlui( adjacent to the serew-outlrt` 1t). vln a device for the purpose set forth, an internally cylindrical casing with a iluidinlet and fluidwutlct, a screW-wl'ieel with its main portion of cylindrical outer contour, fitted in and mounted rotatively Within said I casing .betv-:ccn .said lluid-inlet and outlet.

said screw-wheelhaving a substantiallyspiral blade, the l'ull radial width et said blade increasing from the screw-inlet toward the screw-outlet, and means for gradually reducing the velocity ot the {luiil adjacent to the screw-outlet.

11. ln a device 'for the purpose set forth, a casing with a lluidfinlet and {luid-outlet, a screw-wheel itted in and mounted rotatively Within said casing between said fluid inlet and outlet, said screw-wheel having a sub- 12. A mechanism for thc purpose set forth, having a casing with a .fluid-inlet and llnidoutlet, a screwavlnlel having at its main portion a substantially cylindrical outer contour, iitted in and. mounted relatively within said casing between the {luid-inlet and lluid-out* let, said. screw-wheel having a substantially spiral blade, the full radial width of said blade increasing from the screw-inlet toward the screw-outlet, and adjacent to the screwi so outlet a fixed director.

13. A mechanism for the urpose set forth, having a casing with a llui -inlet and outlet,

a screw-wheel mounted rotatively within said casing between the fluid-inlet and outlet, said scr'etvn'lie l having a substantially spiral blade, and the capacity increasing from thc screw-inlet toward the screwroutlet, the said spiral blade gradually increasing to its full radial width l'roin its inlet end toward 90 the main portion of the screw.

14. A mechanism for the pui )ose set forth, .having a easing with a 'Huid-in et and outlet, a screw-whecl mounted rotativcly within said casing between the iluid--inlet and outlet, said screw-wheel having a substantially spiral blade, theI full radial width of said blade increasing i'roin the serew-inlet toward the screwoutlet-, andthe said spiral blade gradually increasing to its full radial width from its inlet end toward the inain portion of the screw.

l5. A. mechanism for the )urpose set forth, having a casing with a fluid-inlet and outlet, a screwavheel mounted rotativcly within said casing between said inlet and outlet, said screw-wheel having a substantially spiral blade, the capacity increasing troni the screw-inlet toward. the screw-outlet, and the said spiral blade gradually' increasing to its ,110 full radial width lroin cach end toward the i main middle portion ol' the screw.

i6. A rnechanisn'i for the )urlpose set Jforth, having a easing with a Huid-in et and outlet,

a screwavl'ieel mounted rotat-ively within 115 said casing betwecnthe .fluid-inlet and outlet, said screw-wheel having a substantially s iral blade, the full 4radial width of said b ade increasing from the screx '-inlet toward the screw-outlet, and the said spiral blade eradually increasing to its full radial Width om each end toward the rnain middle portion of the screw. l

17. A mechanism for the purpose specified, having a casing provided with an inlet and outlet for' the fluid, a screw-wheel iitted in and mounteil rotatively within said casing between the said fluid-inlet and` outlet, said screw-wheel having a sulistantially spiral i blade, the capacity increasing from the end-portion being gradually enlarged in' ca.

pacity toward the extremity of said end-portion.

A mechanism for the purpose specified, having a casing with a fluid-inlet and Huidoutlet', a screw-wheel fitted in and mounted rota-tively Within said casing between y'the said fluid inlet andoutlet, said screw-wheel having a substantially spiral blade and said blade being limited to the middle portion oi the screw-wheel, the Capacity of the screw 1ncreasing from its inlet towards its` outlet, the screw-body having naked end-portions and annular spaces ,in the casing about said naked endortions, said annular spaces being gradual y enlarged toward the respective extremities of the end-portions. v

1Q. A mechanism for the purpose specilied, having acasing with a {luid-inlet and lluidoutlet, a screw-wheel mounted rotative/ly Within said casing between said inlet and outlet, said screw-Wheel having' a substantially spiral blade, and adjacent to the screw-outlet an annular outlet space which' gradually increases in capacity from the screw-outlet.

20. A mechanism for the purpose specified,

.having a casing with a fluid-inlet and fluidoutlet, a screw-wheel mounted rotatively within said casing between said inlet and outlet, said screw-'wheel having a substantially -spiral blade, with the capacity of the screw lncreasing from. the. screw-'inlet toward thescrew-outlet, and adjacentV to the screwoutlet an annular outlet space which gradu` ally increases in capacity from the screwoutlet.

21. A mechanism for the purpose specified, having'a casing'with a fluid-inlet and -lluidoutlet, a screw-wheel mounted rotatively Within said casing between said inlet and4 outlet, said screw-wheel having. a substantially spiral blade,"theull radial width of said blade increasing from the screw-inlet toward the screw-outlet, and adjacent to the screw-outlet an annular outlet space which gradually increases in capacity from the screw-outlet. l

22. A mechanis'rnfor the purpose set forth, having a casing with a fluid-inlet and fluidoutlet, a screw-wheel, mounted rotatively Within said casing 'between said inlet 'and outlet, said screw-wheel having a substantially spiral blade, and adjacent to the screwoutlet an annular utlet space which gradu- 'ally increasesin `capacity from the screwoutlet, and a fixed director.

23. A mechanism for the purpose set forth, having a casing with a fluid-inlet and fluidoutlet, a screw-wheel mounted -rotatively within said casing,r between saidhuid-inlet 'and outlet, said screw-wheel having a substantiallyspiral blade, the capacity increaseraser ing' from the screw-'inlet toward the screwoutlet, adjacent to the screw-outlet an annular outlet space which graduallyincreases in capacity from the screw-inlet, and a vfixed director. v

Z-l.r A mechanism for the purpose set forth, having,r casing; with a Huid-inlet and fluidoutlet, a screw-whi-el mounted rotatively within said casing between said inlet and outlet, said screw-wheel hanfinur a substantially spiral blade, the full radial width oi said spiral blade increasing from the screwinlet toward the screw-outlet,1 adjacent to the screw-outlet an annular outlet space which gradually increases in capacity from the 'screw-outlet, and a fixed director.

having a casingT with a lluid inlet and fluidoutlet, a scrmv-wheel mounted rotatively within said casing between said inlet and outlet, said screw-wheel A,having a substantially spiral blade and saidblade gradually increasingr to its lull radial width from its inlet end toward the main portion ol the screw and adjacent to the screw-outlet an annular outlet space which gradually increases in capacity -horn the screw-outlet, and a xeddirector.

26. A mechanism for the purpose set forth, having a casing with a duid-inlet and fluidoutlet, a screw-wheel mounted rotatively within said casing between said inlet and outlet, 'said screw-Wheel having a substantially spiral blade, the lcapacity increasing from the screw-inlet toward the screw-outlet, and said blade gradually increasing to its full radial width from its inlet end. toward the main portion of the screw, and. adjacent to the screw-outletV an annular outlet space which gradually increases in capacity in the direction from the screw-outlet`,.and a xed director.

A mechanism for the purpose set forth, having a casing with a fluid-inlet and {luidoutlet, l within said casing between said inlet and outlet, said screw-wheel having a substantially spiral blade the full radial width of said blade increasingv from the screw-inlety toward the screw-outlet and said blade increasing gradually to its full radial width from its inlet end toward the main portion of the screw, adjacent to the screw-outlet an annular outlet space which gradually increases in capacityT in the direction from the screw-olitlet, and a fixed director. i .A

28. A mechanism for the pur ose specified, having a casing provided. witi a lluid-inlet and fluir, -outlet, a vscrew-wheel mounted rotatively within said casing between said inlet etantially spiral blade, adjacent to the screwinlet an annular inlet space which gradually decreases toward the screw-inlet, and adjacent to the screw-outlet an annular outlet a screw-wheel mounted rotatively' and outlet, said screw-wheel having a sub-v 25. A medhanism for the purpose set forth,

ice

ire

. tatively within said easing .let and outlet,l said. screw-wheel having screw-outlet.

29. A mechanism for the purpose specified,

'having a casing provided with a fluid-inlet and fluid-outlet, a screw-wheel mounted rotatively Within said casing between said inlet and outlet, said screw-wheel having a substantially spiral blade, the capacity increasing from the screw-inlet toward the screwoutlet, adjacent to the screw-inlet an annular inlet space which gradually decreases toward the screw-inlet, and adjacent to the screw-outlet an annular outlet space which gradually increases from the screw-outlet.

30. A mechanism for the purpose speciied, having a casing provided with a fluid-inlet and fluid-outlet, a screw-wheel mounted robetween said ina substantially s iral blade, the full radial width of said bla e increasing from the screw-inlet toward the screw-outlet, adjacent to the screw-inlet an annular Ainlet-space which gradually decreases toward the screw-inleth and adjacent to the screw-outlet, an annular outlet space which gradually increases frei/n the screw-outlet.

31. A'mechanisin for the purpose specified, having a casing provided with ailuid-inlet and fluid-outlet, a screw-wheel mounted rotatively within said casing between said inlet and outlet, said screw-wheel having a substantially spiral blade, adjacent tothe screwinlet, 'an annular inlet space which gradually decreases in capacity toward thc screw-inlet,

.and adjacent to the screw-outlet an annular l outlet space which gradually increases in cafrom the sci'e\i'-,outlet, and a lixed dipacity '.rector adjacent to the Aoutlet en d 'of the 40 screw-wheel. i .i

32. A mechanism for 'the purpose specified, having acasing.-provided with a Itluid-inlet andiiuid-"outlct', a screw-wheel mounted rotatively Within said-raising between said inlet and outlet, said screw-wheel having a substantially spiral-blade, the capacityincreasing from the screw-inletloward the screw- Outlet, adjacent to the.screw-inlet :in :innullar inlet space which gradually decreases in capacity toward the screw-iiileu adjacent to. outlet s )ace which gradually increases in capacity il the screw-outlet an annular i'oin the screw-outlet, and a fixed director adjacent t0 the outiet end ol" the smew-n'heel.

' screw-ii'ilet an annular vgradually decreases iiifcapacity toward the l 33. mechanism for the having a 'casing tatively within said casing and outlet, said screw-wheel havinga, substantially spiral, blade., the full i'adial/widtli ot said spii'alblade inceeasingiroin they screwii'ilet toward the screw-outlet, adjacent to the inlet space. which purpose speciiied, provided with a fluid-inlet and-[luid-o-iitlet, a screw-wheel inountedro between said inlet screw-inlet, and adjacent to the screw-outlet 'an annular outlet space which gradually increases in capacity lroin the screw-outlet, and a ixcd director adjacent to the outlet end of the screw-wheel. 34. A nicchaiiisin for the purpose set forth, having a casing with a Huid-inlet and outlet, a screw-wheel having at its inain portion a substantially cylindrical outer contour, fitted between the fluid-inlet and outlet, said screwwheel having a substantially spiral blade, and the capacity increasing from the screwinlet toward the screw-outlet, `thc said spiral blade gradually increasing to its full radial width from one end toward the main portion 'of the screw.

35. A mechanism for the purpose setiorth, having a casing with a'tluid-inlet and outlet, a screw-wheel having at its niain portion a substantially cylindrical outer contour, 'fitted in between the fluid-inlet and outlet, said screwwheel having a substantially spiral blade, the full radial width of said. blade increasing from the screw-inlet toward the screw-outlet, and the saids iral blade gradually increasing to its full ra ial width iroin one end toward the main portion of the screw.l

.having a casing with a tlui -inlet and outlet, substantially cylindrical outer contour, tittcd in and mounted rotatively within said casing between said inlet and outlet, said screw-wheel having a substantially spiral blade, the capacity increasiiigiroin the screwinlet toward the sei'e\\'-outlet radial width t'roni eaeh end toward the inain middle portion ol the screw.

having a serew-wlieel having at its inain portion a substantially cylindrical outer contoi1r,iitted in and mounted rotatively within said casing bel ween the tluid-inlet and outlet, said screwwheel having a substantially spiral blade, the i'ull radial width oi said'bhide increasing from lthe screw-iiilet toward the screnontlet, and the said spiral blade griulually incroasii'ig to itsfull radial width froin each end toward the inain niiddle portion oi the screw.

Si. A inechaiiisin vl'or the purpose having a casing, provided with an inlet` and outletfor the tluid, a. screw-wheel having ai'v its main portion asubstantially cylindrical outer contour,titted in and mounted rotatively within said casing between {luid-inlet and {luid-outlet, said screw-wheel having a substantially spiral blade, the 'c aparity increasing troni the screw-inlet toward the screw-outlet; and said screw- Wheel having a naked end-portion, the annular 36. A mechanism for the dpurpose set forth,

a sci'e\\-wheel having at its main portion av 87. A inechanisnitor thel purpose seti'orth, f

a easing with a lluid-inlet and outlet,

in and mounted rotatively Within said easing and mounted rotatively within said casing and the said spiral blade gradually increasing vto its iull l speeuied, f

the said space s55-de casing about said naked end-portion beting gradually enlarged in capacity toward the extremity. of said end-portion.

39. A mechanism for the purpose specified, havingA a casing provided withV an inlet and outlet, ashaft vmounted rotatively in said casing, and a screw on said shaft within the casing between said inlet and outlet, said screw being at its main portion cylindrical, and having increasing capacity from the receiving end of the screw, and having a naked taper extremity y at its delivery end, substantially as and for thepurpose set iorth.

40. A mechanism 'for the purpose specied, having a easing with a fluid-inlet and iluidoutlet, a screw-wheel having at its main portion a substantially cylindrical outer contour, fitted in and mounted rotatively within said casing between the said fluid-inlet and outlet, said screw-wheel having a substantially spiral blade and said blade being limited to the main middle portion of thc screw- Wheel, the capacity of the screw increasing from its inlet toward its outlet, the screwbody having naked end-portions and annular spaces in the casing about-said naked endportions, and said'annular space being gradually enlarged toward the respcctivc cxtremities of the end-portions.

41. A mechanism for the purpose specified, having a casing with a {luid-inlet and lluidoutlet, a screw-wheel having at its main pci/'- tion a substantially cylindrical outer contour, tted in and mounted rotatively within said casing between said vinlet and outlet, said screw-Wheel having a substantially spiral blade, and adjacent to the screw-outlet an 4annular outlet space which gradually increases in capacity from the screw-outlet. i

42. A mechanism for the purpose speciiied, having a easing with a {luid-inlet and luidoutlet, a screw-Wheel having at its main portion a substantially cylini'lrical outer contour, fitted lin and mounted rotatively within said casing 'between said inlet and outlet, said screw-wheelhaving a substantially spiral blade, with the capacity'nf the' screw inl vcreasing from the screw-inlet toward the screw-outlet, and adjacent to the screw-outlet an annular outlet'space whichgradnally increases in capacity from the screw-outlet. 43. A mechanism for the purpose specified, having a casing with a fluid-inlet and duid-outlet, a screw-Wheel having at its main portiona a substantially /cylindrical outer contour, fitted in and mounted rotal tively within said casing between said inlet and outlet, said screw-wheel having a substantially spiral blade, the lull radial width of said blade increasing from the screwinlet toward the screw-outlet, and adjacent to the screw-outlet an annular outlet space which gradually increases in capacity from the screw-outlet.

l l l l l l l ssfasei 44. A mechanism for the purpose set forth, having a casing with a huid-inlet and {luidoutlet, a screw-wheel having at its main Y `forth, having a casing with a fluid-inlet. and

'fluid-outlet, a screw-wheel having 'at its main portion substantially cylindrical outer contour, fitted in and mounted rotatively within said casing between said fluidinlet and outlet, said screw-wheel having a substantially spiral blade, the capacity increasing 'irom the screw-inlet toward the screw-outlet, adjacent to the screw-outlet an annular outletspace which gradually increases in capacity from they screw-outlet, 'and a fixed director.

46. A mechanism for thev purpose set forth, having a casing with a fluid-inlet and fluid-outlet, a lscrew-wheel having at its main portion a substantially cylindrical cuter contour, iitted in and mounted rotatively within said casing between said inlet and' outlet, said screw-wheel having a substantially spiral blade, the full radial Width of said spiral blade increasing from the screw-inlet toward the screw-outlet, adjacent to the screw-outlet an annular outlet space which gradually increases in capacity from the screw-outlet, and a fixed director.

47. A mechanism. for the purpose sicciiied, having a casing provided with la inidinlet and fluid-outlet, a plurality of screwwheels 'litted in and mounted rotativcly and in series within said casing between the {luidinlet and outlet, 'each screw-wheel havin a substantially spiral blade, and the ill radial width of said blade increasing from the screw-inlet toward the screw-outlet.

4S. 1n a device for the purpose set forth, a casing with a {luid-inlet anduid-outlet, a plurality of rotating screw-wheels mounted in series within said casing between. said duid-inlet and outlet,'each screw-wheel hav- `ing a substantially spiral blade, the full radial width of said blade increasing from the screw-inlet toward the screw-outlet and each screwewheel having a greater screwoutlet capacitythan screw-inlet capacity.

49. In a device for the purpose set forth, a casing with a Ylluid-inlet and fluid-outlet, a plurality of screw-wheels mounted rotativoly and in series within said casing bctwcen the fluid-inlet and outlet, each screwwheel having a substantially spiral blade, the full radial width olE said blade increasing Yfrom the screw-inlet toward the screw-outlet,

eraser the full radial width of said blade and the capacity of the screw-increasing from the screw-inlet toward the screw-outlet, and adjacent to the screw-outlet a iixed director, having a substantially spiral shape.

51. A mechanism for the purpose set forth, having a casin with a fluid-inlet and fluidoutlet, a'plura ity of screw-,wheels mounted having a .rotativcly and in series within said casing between said inlet and outlet, each screw- Wheel having a substantially spiral blade, the capacity increasing from the screw-inlet toward the screw-outlet, and the said blade adually increasing to its full radial `width oineach end toward the main middle portion of the screw.

52. A mechanism lor the purpose set forth, having a casing with a fluid-inlet and [luidoutle't, a plurality of screw-wheels mounted rotatively and in series within said casing between said inlet and outlet, each screw-wheel substantially spiral blade, the capacity increasing from the screw-inlet toward the screw-outlet, and thel spiral blade gradually increasing to its i'ull radial width from its inlet .end toward the main portion of the screw.

' 53. A mechanism for the purpose set forth, having a casing with a fluid-inlet and fluidoutlet, a plurality of screw-wheels mounted rotativly and in series within said casing between the fluid-inlet and outlet, each screwwheel having a substantially spiral blade, the full radial width' of said blade increasing from the screw-inlet toward the screw-outlet, and the said blade also gradually increasingr to itsfull radial width from its inlet end toward the main portion of the screw.

54. A mechanism for the pur )ose specitied, having a casing provided wit a fluid-inlet tand Huid-outlet, a plurality of lscrew-wheels mounted rotatively and in series within said casing between its fluid-inlet and outlet, each screw-wheel having a substantially spiral blade and a naked-end-portion, and the annular space in the casing about said naked end-portion being lgradually enlarved in capacity toward the extremity of said end-portion.

55. mechanism for the purpose set forth, having a casin f with, a fluid-inlet and {luid- Outlet, a pluraiity o i`screw-wheels mounted `rotatively and in series within' said casing bctween its fluid-inlet and outlet, each screw wheel having a substantially spiral blade,

and adjacent to the screw-outlet an annular outlet space which gradually increases in cap acity in the direction from the screw-outlet.

5G. A mechanism for the purpose set forth,

having a casing with a fluid-inlet and fluidoutlct, a plurality of screw-wheels mounted i'otatively and in series within said casing be.-

tween its [luid-inlet and outlet, each screwwheel having a substantially spiral blade, the capacity increasing from the screw-inlet t0- ward the screw-outlet, and adjacent to the screw-outlet an annular outlet space which f gradually increases in capacity in the direction from the screw-outlet.

j 57, A mechanism for the purpose set forth, having a casing with a fluid-inlet and fluidoutlet, a plurality otscrew-wlieels mounted rotativcly and in series within said casing between its fluid-inlet and outlet, each screwwheel having a substantially s iral blade, the full radial width of said spira blade increasing from the screw-inlet toward the screwoutlet, and adjacent to the screw-outlet an annular outlet space which gradually increases in capacity in the direction from the screw-outlet.

A mechanism for the pur ose specified, having a casing provided wit a fluid-inlet and .Huid-outlet, a plurality of screw-wheels mounted rotatively and in series Within saidl casing between the {luid-inlet and outlet, each screw -whecl having a substantially spiral blade, adjacent to the screw-inlet an annular inlet space which gradually decreases in capacity toward the screw-inlet, and adjacent to the screw-outlet an annular outlet ico space which gradually increases in capacity Vfrom the screw-outlet..

59. A mechanism for the pur ose specified, having a casing provided wit i a {luid-inlet and fluid-outlet, a plurality of screw-wheels mounted rotativoly and in series within said casing between its [luid-inlet and outlet, each screw-wheel having a substantially spiral blade, the lull radial width of said blade 1ncreasing froin.the screw-inlet toward the screw-outlet, adjacent to the screw-inlet an annular inlet space which gradually decreases in capacity toward the "crew-inlet, and ad` l rotati'vcly and in series within said casing bel vsaid spiral blade gradually increasing to its 'i having a casing with a fluid-inlet and fluidj and adjacent to each screw-end an annular space which gradually increases in capacity in the direction from the screw. Y

66. A mechanism for the piirpose set forth, having a casing` with a Huid-inlet and fluidjacent to the screw-outlet an annular outlet l space which, gradually increases in capacity from the screw-outlet.

.61. A mech anisin for the purpose set forth, having a easing with a fluid-inlet and fluidoutlet, a plurality of screw-wheels, mounted rotatively and in series within said casing between the fluid-inlet and outlet thereof, each screw-Wheel having a substantially spiral blade, said spiral blade graduall r increasing to its full radial width from one end toward the niain portion of the screw, and adjacent to the screw-outlet an annular outlet s ace which gradually increases in capacity om the screw-outlet.

62. A mechanism for the purpose set forth, havinga casing with a fluid-inlet and Afluidoutlet, a plurality of screw-wheels, mounted rotatively and Wheel having a substantially spiral blade which gradually increases to its full radial width from each end toward the main middle portion of the screw, the full radial width of tie blade increasingl toward the screw-outlet, and adjacent to each screw-end an annular space which gradually increases in capacity in the direction from the screw.

67. A mechanism for the purpose set forth, having a casing` with a fluid-inlet and fluidoutlet, a plurality of screw-wheels mounted rotatively and in series within said casing between said inlet and outlet, each screw-wheel having a substantially spiral blade, adjacent to the screw-outlet an annular outlet space which gradually increases in capacity in the direction from the screw-outlet, and a iixed director adjacent to the outlet end of the screw-wheel.

68. A mechanism for the purpose set forth, having a casing with a fluid-inlet and fluidoutlet, a plurality of screw-wheels mounted rotal'ively and in series within said casing between said inlet and outlet, each screwwheel having a substantially spiral blade, the

inseries within said casing between said lluid-inlet and outlet, each screwwheel having a substantially spiral blade',

full radial width from one end toward the main portion of the screw, the capacity increasing rorn the screw-inlet toward the screw-outlet, and adjacent to the screw-outlet an annular outlet space which gradually increases in capacity from the screw-outlet. 63. A mechanism for the purpose set forth, having a casing with a fluid-inlet and fluidoutlet, a plurality of screw-wheels mounted rotatively and in series Within said casing between said lluid-inlet and outlet, each screw- Wheel having a substantially spiral blade, said spiral blade gradually increasing to its full radial width from one end toward the main portion of the screw, the full radial Width of said blade increasing from the screwinlet toward the screw-outlet, and adjacent to the screw-outlet an annular outlet s ace which gradually increases in capacity rom the screw-outlet. i

64. Amechanisni for the ward the screw-outlet, adjacent to the screwoutlet an annular outlet space which graduually increases in capacity in the direction from the screwfoutlet, yand a fixed director adjacent to the outlet end of the screwwheel.

69. A mechanism for the purpose set forth, having a easingr with a fluid-inlet and fluidoutlet, a plurality ol' screw-Wheels mounted rotatively and in series within said casing, between said inlet and cutlet,"eaal. screwwheelliaving a substantially spiral blade,

theliull radial width ofthe from the screw-inlet toward the screw-outlet, adjacent to the screw-outlet an annular outlet space which gradually increases in capacity in the direction from the screwoutlet, and a xed director adjacent to the outlet end of the screw-wheel;

70. A mechanism for the purpose set forth, having a casing with fluid-inlet and fluidoutlct, a plurality of screw-wheels mounted rotalively and in series within said tween said inlet and outlet, each screwwlwel havingr a substantially spiral blade which gradually increases to its lull radial width from one end toward the main portion ci' the screw. adjacent to the screw-outlet an annular outlet space which gradually purpose set forth,

outlet, a plurality of screw-Wheels fitted in and mounted iotatively and in series within said casing beau/'een said Huid-inlet and outlet, eacli screw-wheel having a substantially spiral blade, said spiral blade gradually increasing to its full radial width from each end towards the main iniddlc portion of the screw, and adjacent to each screw-endan aiinular space which 2ffradually increases in capacity in the direction from the screw.

65. A mechanism for the purpose set forth, having a casing with a fluid-inlet andiluid- I outlet, a plurality of screw-wheels mounted 1 tween its {luid-inlet and outlet, each screwj Wheel havingr a substantially spiral blade which gradually increases to its full radial l width from each cud toward the iniiin middle portion ol' the screw, the capacity increasing l from the screw-inlet toward the screw-outlet, l

outlet, a plurality of screw-wheels mounted, rotatively and in series within said casing between its fluid-inlet and outlet, each screw- Jfrom the screw-inlet blade increasing casing becapacity increasing from the screw-inlet to- ,increasing lto its full radial width end toward Vthe main portion of the screw,

the screw-outlet, and a fixed director adjacent tothe screw-wheel outlet.

`I71. A echanis'm for thepurpose set forth, having a casi with a fiuid-inlet and fluidoutlet, a plura 'ty of screw-wheels mounted rotativelyand in series within said easing between said inlet and outlet, each screwwheel havingv a substantiall -spiral blade, the capacity 'increasing from t e screw-inlet toward the screw-outlet, said blade L radually om one adjacent to the screw-outlet an annular outlet space which gradually increases in capacity inzthe direction from the screw-outlet, and afixed vdirector adjacent to the screwwheel outlet;

72. ,A mechanism for the purpose set forth, having'a casi with a fluid-inlet and fluidoutlet,` a plura ity of screw-wheels mounted rotatively tween; said inlet and outlet, each screwwheel havi U a substantially spiral blade, `the full radila width of said blade increasing from-the screw-'inlet toward the screw-outsaid spiral blade gradually increasi to its full radial width from one end towar the main port-ion of the screw, adjacent to the screw-outlet an vannular outlet space which `gradually increases in capacity in the direction from the screw-outlet, and a fixed director adjacent to the screw-wheel outlet.

73'. l A mechanism for the purpose set forth,

havinga casino' with a fluid-inlet and fluidoutlet, a plurality of screw-wheels mounted rotativelyand in series within said casing be-- an annular space w tween said inlet and outlet, each screw-wheel having a. substantially spiral blade which gradually increases to its full radial width from each end toward the main middle portiony of the screw, ad Lac'ent to each screw-end 'ch gradually increases in capacity in the direction from the screw, and afixed director adjacent to the outlet .end of the screw-wheel.

-having a "casing 74. A mechanism for the purpose set forth, having a casing with a fiuid-inlet and fluidoutlet, a plurality of screw-wheels mounted rotatively and in series within said casing be- -tween said inlet and outlet, each screw-wheel having a substantially spiral blade, the capacity increasing` from the screw-inlet toward the screw-outlet, said blade graduali increasing to its full radial width from eac end toward the main middle portion of the screw, adiacent to each screw-end an annular space which gradually increases in capacity inthe direction from the screw, and a fixed director adljaccnt to the outlet end of the screw-whce 75. A mechanism for the purpose set forth,

`with a fluid-inlet and fiuidoutlct, a plurality of screw-wheels mounted rotatively and in series within said casing beincreases in capacity in the direction fromand in'series within the casing be- -ing through said compartments,

A outlet of t-he casing,

tween-said inlet and outlet, each-screw-wheel.

having a substantially spiral blade which radually increases to its full radial width om each end toward the main middle ortion of the screw and the full radial width of said blade increasin r from the screw-inlet toward the screw-outlet, adjacent to each screw-end an `annular space which gradually increases in capacity in the direction from the screw, and a fixed director adjacent to the outlet end ofthe screw-wheel.

7 6. A mechanism for the purpose specified, having a casing with an inlet and outlet and divided into compartments, a shaft rotatively mounted in said casing and extending through said compartments, screws of opposite pitch on said shaft and in the respective compartments, said screws each having a substantially spiral blade, and its ca acity increasing from the receiving toward tlie delivery en of the screw, and a conduit which compels the fluid to pass in series through the screw-wheels but in opposite directions, substantially as set forth.

77. A mechanism for the purpose specified,

com rising an elongated casing having a flui -inlet and fluid-outlet, and being divided into two separate compartments, a shaft iotatively mounted in said casing and extending through said compartments, a plurality of screw-wheels secured on said shaft and mounted rotatively and in series within the compartments between the `fluid-inlet' and o utlet of the casing, each screw-wheel having a substantially spiral blade and its capacity increasing from the screw-inlet towardl the screw-outlet, butthe several screw-wheels being respectively of lreverse pitch within the respective compartments, means com elling iuid to pass in opposite directions an .in series through the two compartments and the screw-wheels located therein.

78. A mechanism for the purpose specified, comprising an elongated casing having a fluid-inlet and fluid-outlet andbeing divided into two separatecompartments, a shaft r0- tatively' mounted in said easing and extenda plurality of screw-wheels secured n said shaft and mounted rotatively and in series within the compartments between the fluid-inlet and a substantially spiral blade, the full radial width of which increases from the screw-inlet toward the screw-outlet, but the respective screw-wheels being of opposite or reverse pitch within the respectlve compartments, means compelling fluid to pass in opposite directions and in series through the res ective compartments and the screw-wheels ocated therein.

79. v mechanism for the purpose set forth,

comprising an elongated casing having a fluid-inlet and fluid-outlet and being divided into two separate compartments, a shaft roeach screw-wheel having ilo tatively'mounted in said easing and extending through said compartments, a pluralityl of screw-wheels secured on said shaft and mounted rotatively and in series within the compartments between the fluid-inlet and outlet of the casing, the blades of said screwwheels .being of opposite or reverse pitch in the respective compartments, each screwwheel having a substantially'spiral blade, the capacity increasing from the'screw-inlet toward the screw-outlet, said spiral blade gradually increasing to, ts full radial Width from each end toward the; mainmiddle portion of the screw, adjacent to each screw-end an annular space which gradually increases in capacity m the direction 'from the screw, adjacent to the screw-.wheel outlet a fixed director,

. andv means compelling the fluid to pass in screw-Wheels located opposite directions through the respective lcompartments successively, and through the therein in series. 80. A mechanism for the purpose specified, comprising an el ongated casing, having a f fluid-inlet and fluid-outlet and beingdivided into two separate' compartments,a plurality of screw-wheels, fitted in and mounted rotatively within the two compartments between the fluid-inlet and fluid-outlet, each screw-wheel having at its main portion a substantially cylindrical outer contour, and having a substantially spiral blade, the capacity increasing from the screw-inlet toward the screw-outlet, the several screwwheels being connected endwise but being of opposite or reverse pitch within the respective compartments, means compelling the fluidto pass in opposite directions but 1n series through the two compartments, and in series' through` the screw-Wheels located therein. v

81,. A mechanism for thefpurpose specified, comprisin fluid-inlet and fluid-outlet and being divi into two separate compartments, a pluralitj)r of screw-wheels, fitted in and mounted rotatively within the two compartments bel but boing of opposite or reverse pitch within the f' respective compartments, means compelllpg the fluid to pass in opposite directions but in series through the two compartments, and in series through the screw-wheels located therein.

82'. A mechanism for thc purpose specified, having a casing with a fluid-inlet and fluidoutlet, and divided into separate compartments, a pluralityv of screws, being at their respective mam portions of substantially cylindrical outer contour, fitting and mounted rotatively within the 'respective 'compartments, but being of opposite or reverse pitch within the respective compartments, each screw having increasing capaci-ty from the receiving end Itoward the delivery end, the several screw-wheels being connected with each other endwise, a conduit or by-pass which compels the fluid to pass in series but in opposite directions through the several compartments and through the screw-Wheels mounted therein.

l83. A mechanism for the purpose set forth, having a casing with an inlet andan outlet, a shaft mounted rotatively slidable endwise, a cylindrical piston-chamber through which' the shaft extends, said piston-chamber having two inlet-ports, one .at each side of said piston and an exhaust port at thermiddle portion `of said pistonchamber, a piston on said shaft and controlling said exhaust-port, and means for admitting fluid'under pressure to the, pistonchamber at both sides of said iston,I Whereby the endwise' movement an thrust of the shaft is controlled.

84. A mechanism for the purpose set forth, having a casing With a Huid-inlet and fluidoutlet, a shaft mounted rotatively in said casing and slidable endwise, a cylindrical piston-chamber through which the shaft extends, said piston-chamber having a fluidinlet port near each end, an exhaust port near its middle or center portion, a piston secured on said shaft Within the pistonchamber, means for admitting fluid lunder an elongated .cas1ng, having ay pressure at said inlet ports, the piston controlling the exhaust port which 1s normally closed by said piston, said exhaust port being opened at either side of said pistonif there. is an end-wise movement of the shaft, thus controlling automatically the shaft by relieving the pressure on said piston in the direction of the end-thrust.

ber through which .the shaft extends, said piston-chamber having an exhaust port near its middle or center portion, a piston secured on the shaft and fitting p eripherallysand ro-.

.tatively within the piston-chamber,'rnenS for admitting fluid under pressure tb said chamber through separate inlet ports at both sides of said piston, the latter controlling said exhaust-port which is normally covered by the piston, the exhaust-port being opened at one side or the other of said piston if there is an cndwlse movement ofthe shaft.

86. A mechanism l'or the purpose set forth, having a casing with a [luid-inlet and fluidoutlet, a screw-Wheel with its main portion having a substantially cylindrical outer contour and being fitted in and. mounted rotatively within said casing between the fluidin said casing and' the end-thrust lon Y 85. A mechanism for the purpose set forth,

outlet, a shaft mounted rotatively in said the piston, said exhaust-port being opened at one side or the other ol the piston il there is im endwise movement. ol` the Shaft.

Inlwitness whereof l luwo hereunto signed 15 my name this 23d doy of July, 1903, in the presence 'of two subscribing witnesses.

FRANZ MARBURG, J R.

inlet and fluid-outlet, a, shaft on whieh tho screw-Wheel is mounted, and u piston-olmo ber fhrough which the shaft extends, solo iston-ohamber having an exhaust-port near lts middle or center portion, a piston scoured on said shaft and ttng periplremlly und rotatively Within the pston-ohomber, owons corradrnttng Huid under pressure to sold chamber through Separate nlot ports :Lt holh sides of the piston, the lutter controlling solo eXhimSt-porl which is normally oovorwl hy l W it messes:

HENRY CONNETT, WILLIAM J. Fm'fn. 

